1. Field of the Invention
The present invention relates to a technique for remotely ascertaining electrical conditions in drive circuitry.
2. Description of the Prior Art
Electrical circuitry, such as electrical drive circuitry for controlling the speed, torque and/or power output of one or more electric motors, is commonly supplied with a plurality of test points throughout the circuitry. A test instrument may be connected to the test points to ascertain appropriate electrical phenomena in the circuitry and its operative condition. In improved types of drives, the test points are wired to a multiple position switch, which in turn is connected to a test instrument, such as a meter. By moving the switch to the various positions, the test points in the circuitry are connected to the meter. Scaling circuitry may be interposed between the test points and the meter to accommodate a variety of electrical phenomena on a single meter and the meter may be provided with a plurality of scales.
Instruction manuals are provided by the manufacturer of the electrical circuitry to the purchaser-operator. These manuals detail test and trouble shooting procedures including the sequence of the test points or switch positions necessary for the diagnosis and analysis of the probable faults in the circuitry.
Such procedures are not altogether satisfactory. In the event the operator cannot diagnose the cause of the faulty condition, he ordinarily telephones the technical service personnel of the manufacturer explaining the symptoms and manifestations of the fault and the associated electrical phenomena. Under such conditions, the service technician is frequently unable to assist the operator of the circuitry. The operator may unrealizingly not be following the correct test procedure and may be reporting incorrect data. Or, the operator may be following the correct test procedure but misinterpreting the data. Or, the operator may simply not be able to describe the situation over the telephone sufficiently to enable the service technician to ascertain the fault.
The result is often that the service technician is required to make a service call to correct what is, in reality, a minor problem. This is expensive for the operator and time consuming for the manufacturer, particularly where the equipment is found in a remote location.